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First oscilloscope

Discussion in 'Electronic Basics' started by [email protected], Mar 22, 2008.

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  1. Guest

    Hi all,

    I do pic programming, Ir circuits, analogue circuits and use 433MHz AM

    I want to get an oscilloscope to analyse the circuits I build and,
    currently, to analyse the output from IR remote controls. However, I
    know nothing about them!!

    Can someone tell me what I need to look for in an oscilloscope and
    make recommendations on what would be suitable?


  2. How much money do you have to spend?

    Ideally you want two of them. A good traditional analog oscilloscope,
    and a digital storage oscilloscope.
    To analyse the output from IR remote controls requires you to capture
    and display the signal, this requires a digital storage oscilloscope.
    However the requirements of this are very simple and could be covered
    with a cheap USB PC oscilloscope.

    With both types you pay more for more *analog* bandwidth.
    60-100MHz is a good starting point these days.
    With digital oscilloscopes you pay more for *sample memory* and sample
    rate. The more sample memory the better. Ensure that the sample rate
    is at least 10 times the analog bandwidth. e.g. a 100MHz bandwidth
    digital scope should have a 1GS/s sample rate. A good size sample
    memory starts at say 8K and goes upwards.
    You get much better value-for-money with a second hand oscilloscope
    from Ebay or a surplus dealer, especially for analog types. e.g. you'd
    be a bit foolish to buy a brand new 100MHz analog oscilloscope, they
    are expensive.
    But brand new 20MHz dual channel analog scopes are fairly cheap these
    days, that is a decent starting point.
    With eBay you take your chances somewhat, but buying from a reputable
    dealer who has extensively tested (and possible calibrated) the unit
    can be a good way to go.
    Digital scopes are fairly expensive, and the second hand market is not
    big, but if you have the money then get a good one over a USB based PC
    oscilloscope. You need to buy a very expensive digital scope to get
    good "analog like" performance, that's why I recommend getting a good
    analog scopes too.

  3. Yukio YANO

    Yukio YANO Guest

    A sound card based PC Scope would be ideal. The P/H to buy a even the
    cheapest Hardware Scope would exceed the cost of the software for a PC scope

    The IR remote runs around 15 KC so using a 100Mhz Scope would be like
    using a 4 engined Water-Bomber to water the Lawn. Effective, just not
    cost effective. Digital would be nice, but again it's like using a
    Micrometer to measure cut firewood !

    The 433Mhz PIC is just a Red Herring !
    Yukio YANO

  4. How do you know that? 433 MHz is used for remote controls, and
    garage door openers.

    -- is home to cowards and terrorists

    Add this line to your news proxy nfilter.dat file
    * drop Path:*!not-for-mail to drop all traffic.
  5. Eeyore

    Eeyore Guest

    Get any decent secondhand Tektronix.

    You can't go wrong with a Tek, much as the same way you can't go wrong
    with a Fluke DMM.

  6. Rubbish, it would be the worst possible solution.
    You at least need a proper front end amp/attenuator for such a thing,
    and even then you are limited to audio bandwidth only.
    Unless the OP's "analog circuits" are all audio bandwidth and line
    level type signals, forget it.
    Hardware scopes can be had for FREE if you look hard enough.
    People (including myself) have given away scopes for free before on
    this and other groups.
    Beginners can ask and they often get a lucky donation.
    Wrong. They are around 38KHz.
    That's not the point. The point is having a general purpose tool that
    can do all sorts of jobs.
    100MHz is not overkill for a general purpose scope. Want to measure a
    basic 20MHz digital signal for instance, 100MHz comes in handy.
    Digital is essential jobs like capturing IR data packets.
    A logic analyser is often handy for this too.
    Ah, 433MHz is used for all sorts of stuff.

  7. Guest


    Hi all,

    Thanks for the informative replies - lots to think about!

    Unless there is a kind person out there who wants to hand me a
    hardware scope I think the best option would be a USB PC scope. It'll
    allow me to do IR analysis which is what I really want to look at for
    now and should allow me to analyse more basic circuits. If I reach
    it's limitations I can look into a more expensive (digital) solution.

    Which brings me onto my next question - what USB scopes are out there
    and which make(s) are worth considering??

    I'm still a bit unsure on the bandwidth issue....if IR runs at 38Khz
    then a 25Mhz scope should be able to see the signal very clearly
    shouldn't it? Also, the maximum speed I run PICs at is 20Mhz but
    that's divided by 4 to give a real speed of 5MHz. If the output
    signals actually ran at this speed (unlikely because it wouldn't give
    the PIC time to do anything else, would a 25MHz scope be able to
    display them?


  8. Not a bad idea.
    The question is still how much would you be looking to spend?

    To analyse IR data packets you might need a reasonable amount of
    sample memory. 8K is probably the minimum you'd want to look at, but
    the more the better.
    Some USB scopes might sample in real time to the PC, so they could
    effectively have have unlimited sample memory (at lower sample rates)
    Yes, it's plenty.
    25MHz bandwidth - yes
    25MHz sample rate - that's starting to push it.

  9. Jamie

    Jamie Guest

    A 25 Mhz is just fine. try to get a stand alone bench or hand held that
    has the PC connection and software..
    I my self bought a OWEN hand held for my toss around tool box scope,
    that's a 20 Mhz and It just happens to have a DMM also along with
    isolated inputs between all inputs.. $499, is what I paid for it and I
    find that for the price and what it does, it's great for moderate work
    and for most maybe even over kill.

    they make a 60 Mhz version of the same unit.

    For anything high in freq, I keep a Tek Analog
    350 Mhz scope around for that."
  10. Bob Masta

    Bob Masta Guest

    On Sat, 22 Mar 2008 07:47:04 -0700 (PDT),
    You may want to consider having both a (used) hardware scope along
    with a PC soundcard program. (OK, I might be a tad biased since I am
    the author of one such program!) I have a 100 MHz "real" scope plus
    a sound card system on my bench, and they both have their virtues.

    The hardware scope is best for all general purpose work. The sound
    card system suffers from being AC coupled, and limited to audio-range
    signals. But if you are working in the audio range, there are some
    powerful advantages: It does spectrum analysis and color
    spectrograms, as well as all sorts of tricks like histograms, and
    synchronous waveform averaging to extract signals buried in noise.

    If you are working on something where you need to monitor distortion,
    a conventional scope's waveform display is *not* the way to go:
    Depending on the type of distortion, you might miss several percent
    distortion on a sine wave display, whereas on a spectrum display you
    can easily see a tiny fraction of a percent. Not only that, you can
    see exactly which harmonics are causing the trouble (which can be
    a clue to the source of the distortion).

    As an example, if you build a triangle-to-sine shaper using an
    overdriven differential pair, there are a couple of interacting
    adjustments that can be really confusing to adjust by just looking at
    the waveform (or by ear). But they are a snap if you can watch the
    relative harmonics go up and down on a spectrum display.

    And sound card systems can be dirt cheap, especially with the easy
    availability of old computers these days.

    And if that isn't enough to convince you, there's the fact that sound
    cards can also *generate* sound... with lower distortion than
    most benchtop audio generators, and *much* lower distortion than
    function generators. But they can provide much more control than any
    function generator, not only in offering many types of waveforms,
    including different kinds of noise, but also in types of modulation
    like bursts, AM, FM, PWM or PM, or sweeps.

    (Product plug: The Daqarta signal generator is FREE, even if you
    never buy the system. Oh, yeah: Daqarta also includes a big-screen
    DMM with true RMS, peak, and dB options, plus a frequency counter
    that can resolve to milliHertz in a few cycles, even at low audio

    Best regards,

    Bob Masta

    DAQARTA v3.50
    Data AcQuisition And Real-Time Analysis
    Scope, Spectrum, Spectrogram, FREE Signal Generator
    Science with your sound card!
  11. You can get you a vellman PC500 scope for about 300 bucks wich is suppose to
    be 50mhz(which is 50MSPS and I don't see how it sends all that through the
    parallel port which runs at most a few mhz or so).

    The only reason I recommend this scope now is because they finally
    implemented a history function. When I first brought it I thought it would
    have this feature but didn't. I complained on the msg board and was told
    that it was impossible and I didn't understand how a DSO worked(by the
    company). So I gave up and 2 years later I tried again and somehow got
    through to the guy that maintained the software and he was able to implement
    it. The software is definitely not the best though but works.

    So the point is that with that scope you can use it both as a oscilloscope
    and a logic analyzer(although a bit crude it does work). This is really the
    only benefit it has is that its cheap and can do the two most important
    things needed for most apps. It is definitely not the best though but you
    get what you pay for. If you have more money then I'm sure there are other
    products that would be better. (in fact you can get cheap dedicated logic
    analyzers too now that use the pc)

    I would have to say that the real issue with the scope is mainly the
    software though. But you can get used to it and maybe in the future they
    will release the protocol used so people can write there own software. (they
    do have something like it but not full featured)
  12. Guest

  13. PinkFloyd43

    PinkFloyd43 Guest

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